This invention relates to helmet mountable displays, ard, more particularly, to a self-contained, full color, wide angle, light weight, inexpensive, stereoscopic, high resolution helmet mountable video display, such as may be used in simulation systems like trainers, or during actual vehicle or aircraft operation as a display for sensors and/or instruments.
One type of helmet display system using helmet mounted CRT's, head and eye tracking, and an optical lens system with a beam splitter for rendering a desired image is shown and described in U.S. Pat. No. 4,028,725 - Lewis. Another type involving a projection onto a screen using optical guide with rotary joints and a counterbalance for relieving weight from the pilot's head is illustrated and described in U.K. Patent Specification 1,489,758.
Yet another type, which employs a separate fiber optic light guide for generating each line of a raster, is shown and described in U.S. Pat. No. 4,349,815 - Spooner. For the latter system, as the number of lines increases, granularity may be expected to increase and overall quality of the image may be expected to decrease, since it is difficult to maintain uniform optical characteristics among all the light guides.
U.S. Pat. No. 4,097,115 - Garwin et al illustrates an optical scanning device that uses a plurality of light sources for producing adjacent lines in a band for a display. Light from the sources is reflected onto a screen by a horizontally deflecting element and the reflected image from the screen is reflected by a vertically deflecting element to an observer. Focusing an image on the screen limits the field of view (FOV) obtainable from the device. Further, using a plurality of light sources to portray adjacent lines of the same band does not significantly reduce the bandwidth of the vertical scan. Also, it is not clear whether stereoscopic vision can be obtained from images reflected from the single screen, since the screen is provided with a textured surface stated to provide a controlled degree of scattering power.
It would be desirable to provide a helmet mountable display system that overcomes the disadvantages and inconveniences of the known art. Further, it would be desirable to use an electro-mechanical scanning system wherein the physical scan requirements are reduced over those of known systems.
Accordingly, it is an object of the present invention to provide a helmet-mountable display system that is light-weight and inexpensive, and that provides a full color, high resolution wide-angled image to a viewer.
Another object is to provide a stereoscopic image display system having an electro-mechanical scanning system wherein any scan anomaly affects each eye's image equally to assure registration of the images.
Still another object of the present invention is to provide an image display system having an electro-mechanical scanning system incorporating multiple simultaneous scan lines for reducing video bandwidth and physical scan angle requirements.